Update changelog for v0.15.0

[gha-automation-personal]

Changes

This PR prepares the changelog for release v0.15.0

🚀 New Features

• Add rename command by @Copilot in Add rename command #366
• Auto-select stack when current branch is only in that stack by @Copilot in Auto-select stack when current branch is only in that stack #370
• Improve conflict detection by @geofflamrock in Improve conflict detection #368
• Improving logging and status display by @geofflamrock in Improving logging and status display #360
• Add json logging by @geofflamrock in Add json logging #373
• Improve squash merge handling by @geofflamrock in Improve squash merge handling #379
• Add branch move command by @Copilot in Add branch move command #367
• Default to updating stack without checking pull requests by @geofflamrock in Default to updating stack without checking pull requests #380

🐛 Bug Fixes

• Fixes issue where gh cli error would cause commands to fail by @geofflamrock in Fixes issue where gh cli error would cause commands to fail #372
• Fix rebase and merge operations when branches are checked out in worktrees by @Copilot in Fix rebase and merge operations when branches are checked out in worktrees #362
• Skip child action prompt when removing branches with no children by @Copilot in Skip child action prompt when removing branches with no children #382

Other changes

• Add integration tests for StackActions by @Copilot in Add integration tests for StackActions #377

Releasing the new version

When you are ready to release the new version, merge this PR, then create a release in the repository with the tag v0.15.0.